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Most cheap USB webcams can see IR, especially if you remove any IR filters inside them. With the camera that I'm currently using, the IR from the LEDs that I'm playing with (wavelength unknown) shows up as a blue-tinted white color.

IR LEDs are available at Digikey in wavelengths going from 830 nm to 950nm. Are there any cheap USB cameras that can see different wavelengths of IR as different colors? While a purpose-built IR camera would be best, those are expensive, so I'd settle for a camera that just reacts differently to different wavelengths. Even a relatively small tint difference would be good, as I can put a visible-light filter on the camera and capture only the IR.

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I suppose I could just buy a whole array of them from Digi-key for $20 or so, put them in a line, and see what the camera sees; I wouldn't mind a better solution, though. – Aric TenEyck Feb 5 '10 at 22:11

Maybe this can help: It is very neat trick with Wii remote control - IR camera inside with 1024x1024 resolutions. Bluetooth connection with your PC build-in.

A lot of interesting hack has been done with it.

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Actually, my early work was with Wii remotes - I'm moving to cameras because Wii remotes have a very narrow field of vision and a limit of four distinct points. I was hoping for an additional ability to distinguish points. – Aric TenEyck Feb 10 '10 at 19:55
you probably can extend the field of vision by just putting a fisheye lens in front of it. – Egon Feb 16 '10 at 17:36
And for multiple points you probably have to remove the ir camera from the wiimote and hack it... – Egon Feb 16 '10 at 17:41

Not quite sure what you are trying to do - only visible light makes sense to us from a color perception point of view.

Are you trying to make a cheap thermal camera? You probably already know that the images from those are in pseudocolor, that is, they return a monochrome image to which a colormap is applied to map intensities to color. Also, thermal cameras detect much longer wavelengths than a normal CCD or CMOS sensor can detect, so your cheap webcam sensor won't work.

If you are trying to highlight certain parts of your scene that reflect specific wavelengths of IR, you could try:

Filters Bandpass IR filters are quite expensive, but if you can afford them, taking multiple photos with different bandpass IR filters in front of the sensor would work, and you would get the images at each IR band at the full resolution of your sensor. (Assuming your remove the IR / Bayer filters first.)

Illumination If you know the specific wavelengths you want to see, then try illuminating your scene with LEDs that emit light of known wavelengths. You would then have multiple images of your scene reflecting known wavelengths. Assuming there is no fluorescence or any other wavelength shifting phenomenon, then you'll be okay.

If you are just trying to colorize your IR photos, then converting to monochrome with a tint or a duotone in Photoshop/GIMP is your best bet.

Good luck!

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I'm playing with motion tracking; I'd like to put multiple LEDs into the scene and track their position with a camera. As I mentioned, my current LEDs show up on my current camera as a blue-tinted white, so it's not unreasonable to hope that other wavelengths might show up as other colors. I was hoping that someone had experience with this or knew of a good camera for doing it. – Aric TenEyck Feb 8 '10 at 14:01

The bayer matrix would reject the near-IR wavelengths in green and blue, so only a red image will show. Unless you are viewing in grayscale mode.

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Long answer short; IR will always show up as RED (That's why it is called infra-red).

I fail to understand how an IR LED can show up as blue-white. It should be red (with a little white mixed in at best). You've possibly got your camera's white balance screwed up and are also capturing visible light along-with the IR light (affecting the image color).

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Nope. Get a remote control, and look at the front of it with a digital camera; you'll see a white flash every time you press a button. There's no reason that IR would show up as red; light stops being 'red' once you stop being able to see it, which happens at about 700 nm. – Aric TenEyck Feb 16 '10 at 21:14

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